Furnace stoker



J. S. BENNETT FURNACE S'I-OKER Oct. 17, 1933.

Filed Sept. 25. 1931 gh wws Patented Oct. 17, 1933 ,1,931,2s1.ffj H W [FURNACE s'roKmr a 1 Joseph s. Bennett, Philadelphia, ra-[assignort'o American Engineering Company, Philadelphia, Pa, a corporation of Pennsylvania w Application September 25, 1931* Serial No. 565,160

5' Claims. (or. 122-376) This invention relates to improvements in furnace stokers, and the invention in principle has an application of particular value to the over feed sections of underfeed stokers of the general type disclosed in the pending UL S. application of Herbert E. Preston, Serial Number 263,900. One object of the invention is to providefa stoker incorporating novel means for cooling the fuel-supporting elements.

Another and more specific object of the invention is to provide a novel design of stoker parts permitting regulated cooling 'of the parts by means of a liquid-cooling medium.

Still another object of the invention is to provide in a stoker of the multiple retort underfeed type, a novel design of overfeed section wherein provision is made for cooling 'said section by means of aliquid-cooling medium.

A still further object. of the invention 'isito provide a novelJand improved form' of ease;

' sion grate having provision or circulating a fluidmedium in conductive relation with the fuelsupporting elements of the grate..

Another object is to providea novel. and 'ims. proved form of fluid-cooled lower. grate struc ture.

Still another object is to provide in conjunction" with 'stoker-parts as set forth above, a system oi low-grade fluid-cooling whereby theQte'm pera l tures of said parts may be maintained below. the burning or fusion pointwithout extracting appreciable amounts of heat from the furnace.-

' The invention further resides in certain novel and improved structural features and mechanical details hereinafter set forth andillustrated in the attached drawing, in which:

Figure 1 is a more or less diagrammatic vertical sectional view of the lower. or overfeed section of a multiple retort .underfeed stoker wherein said parts are constructed in accordance with the present invention, and I.

Fig. 2 is a section on the line 2-2; Fig. 1.

With reference to the drawing, the reference numeral 1 designates generally the lower or overfeed section of a multiple retort underfeed stoker of the general type disclosed in UQS'. Patent No. 1,443,202, this portion of the stoker'being mounted in the present instance upon an underlying supporting structure 2. The overfeed section comprises the dead plate 3 in which the retorts and tuyeres (not shown) terminate and onto which the fuel is emptied from the said retorts by action of the fuel-feeding elements. Mounted below the dead plate 3 is an extension grate 4 which in the present instance is. adapted tor. forward and backward reciprocation between thefdeadplatefi and the lower grate I 5, whichilatter constitutes theflf orwardwall of the'stoker-ashpit. In the bottom of this pit is mounted'injthe presentinstance a pair of crusher rolls 6,"and' the said forwardfwall of the ash bit. is illustrated as comprising; at

the lower portionand' adjacent one of thecrush= er rollsv 6 a crusher plate. 17 whose function is well understood in the art andgwhich constitutesno partof thepres'entinvention. I, the present in tance, the extension grate 41s composedjof a plurality of transverse sec ti'ons," a cross section'al view of 'one of ,whlchls shown in, Fig. 2,' and these sections are reciprocatedbvmeans in the present instance of rods 8 attached to thejrespective grate sections and connectedto suitable actuating mechanism (not shown')..

. Inaccordance withgmy invention, the extension 7.5 grate sections are formed in the upper or ifuel+ supporting section with a series of channels 9 g l which in the presentinstanceextend from the upper ,forward edgeofjfthe grate to the lower rijearjed'ge; and intermediate thesecliannels are fo'rmedlseries of passages .11 which extend from the lower-T to the upper; surfaceloi 1 the grate and which constitute means for. passing combustion .airthrough the grate to the fuel-bed. ,Ihtdfthe upper lend of. each of the channels .9' extends'a pipe.1:2, these 1 pipes being connected inf'the' present instance toiithe hollow interior ofQthe dead plate -3',' thedeadplatein effect constituting a reservoir fronrwhich water .is fed tofthe 'extension grate. 'Tho'sepo'rtions 'ofthepipe 12 which enter the channels'9 extend parallel to the direction of'movement of theextension grate sections and are of sufficient length toafiord the extension grate. sections a normal movement while maintaining intact the fluid connection between the pipe and the said channels 9.

Extending forwardly from the lowerv end of each of the channels 9 and under the grate .4 is a pipe 13 which at its extremity extends downwardly and again towards the rear of the furnace and into the, interior of the lower grate 5 at the upper end of the latter. The pipe 13 is of sufii cient length to afford 'a maximum movement of the extension grate in its normal reciprocation while maintaining the fluid connection between the pipe and the interior of the lower grate 5.

The lower grate 5 is shown as composed of a series of blocks 14 superimposed. one upon the other and suitably supported in the relatively conform to that disclosed in the aforesaid U. S.- application, Serial Number 263,900, although it f the structural details may vary widelywithout ,rect contact with the incandescentfuel.

fixed structure of the lower portion of the stoker. In general construction, this lower grate may may vary widely as to structural details. Each of the blocks14 is shown as having at its inner surface an inclined surface *15, and these surfaces on adjacent blocks are inclined to the vertical in reverse directions and are so relatively located that the lower end of one overlies a portion of the immediately underlying surface. The arrangement is such that water discharged from the pipe 13 and directed against. the surfaces 15.

of the upper series of blocks through'the-mee dium of a baflie 16 will be directed over'the faces of each of the inclined surfaces 15 of the entire series of underlying blocks, this water eventulation o'fwater, a highly eflicient cooling of the dead plate'B, the extension grate and the lower grate 5. is eifected, 'These elements, constituting the overfeed. section of the stoker are subject to extremely high temperatures by reason ofdi- In accordance with my invention, maintenance of these. elementsris materially aidedr by'provision of cooling means so regulated as to maintainthe elements at temperatures below the point of burning or fusion while at the same, time not withdrawing any appreciable" heat from the fur nace. The degree or amount of coolingma'y be variedas requirediby simple regulation of the water'supplytothe dead plate 3. f

It will be'apparent that jtheinventionin prin-- ciple is applicable to other than the overf'eed sections of mechanical underfeed stokers', and

that as regards' the specific embodimentYof the invention shown for the purpose of illustration,

departure from the invention;- fWhileffor e ample, the water'in the illustratedembodiment flows, through the dead plate 3 to the extension grate,'and thenceto'the lower grate, it'is apseparate source of supply.

, parent that each of these elementsmay have a -derfeed stoker, the combination with a hollow dead plate constituting a reservoir for a liquidcooling medium, an extension grate mounted below said dead plate, said extension grate being formed with a plurality of channels in the fuelsupporting portion thereof, and means for conducting liquid from said dead plate into the 'upper ends of said extension grate channels, said means providing for movement of said extension grate relative to the dead plate while maintain ing intact the fluid connection: 7 3. A stoker comprising an extension grate and a lower grate underlying said extension grate, said extension grate being formed with a plurality of channels for passage therethrough of a liquid-cooling medium, and means for discharging the liquid from the said channels over the surfaces of said lower grate.

4. In a stoker, a grate structure comprising a series of elements forming a wall, said elements having at the rear inclined wall surfaces the lower edge of each of which overlies the upper portion of an underlying surface, and means for directing a fluid against one of the said inclined surfaces whereby the said liquidflows bygravity over thesurface's of; the underlying elements.

.5. In a device of the class described, the combination o'f'a lower grate, comprising a series of superimposed elements, each 'of said elements having a heat absorbing surface-and a heat dissipating surface, the'lattersurface of one element being inclined in a different direction than the corresponding surface of the next adjacent element, and means for directing a cooling medium against said last named surfaces. 1 6. In a device of the class described, the combinationof alower grate, saidgrate having a heat absorbing portion and a plurality of heat dissipating portions, said last mentioned portions beingal'ternately inclined in different directions and having outer and imiersurfacesjand means for directing a coolingmedium against said last named portions so that said'mediLLm alternately JOSEPH -SQ1BENNETT. 

